the kentucky derby weekend is usually all about the big hats and mint juleps. and of course, the horse races. but nearly three weeks after this sporting event ended in tragedy, folks here are thinking about more than just waging their bets. >> it's what happened in boston, is it on your mind today? >> yes. it's definitely on my mind, just for the fact it's such a large crowd. you just never know how people's intentions are. >> absolutely. me and my buddy are coming from chicago. we were both talking today about, how scared at all about it? obviously it's on the forefront of our minds coming in today. >> reporter: security has been tight at the derby since 9/11. but now officials are cracking down even more. >> the first thing you do after an event like that is you just get everybody back together and you say, what's the plan? do we need to make any adjustments? >> reporter: among those adjustments, a ban on coolers, cans, even large purses which came as a surprise to some. 100 additional officers from federal, state and local agencies were brought in to conduct